The invention relates generally to antennas for receiving RF signals and more particularly increasing the sensitivity of a resonant cavity formed on a printed circuit board.
Some antennas formed on circuit boards have a resonant cavity defined by a ground plane on one side of the circuit board, a formed piece of stripline referred to as a stub on the other side of the circuit board and an electrical connection between them. The shape and length of the stub determines the resonant frequency of the cavity. Generally, the stub is formed of stripline shaped on a circuit board. However, due to their flat nature, antennas formed on circuit boards principally receive signals in the direction normal to the plane of the antenna and arriving at the stub side of the circuit board. Signals arriving at the ground plane side of the circuit board are substantially blocked from the cavity.